1. Field of the Invention
The present invention relates generally to the field of trailers drawn by motor vehicles. More specifically the present invention relates to a trailer for transporting a vehicle such as a motorcycle, the trailer including a perimeter frame supported by trailer wheels and a motorcycle support bed mounted within the perimeter frame on a line and pulley elevation mechanism. The line and pulley elevation mechanism lowers the bed to load and unload the motorcycle and elevates the bed for motorcycle transport, such that the plane of the bed always remains substantially parallel with the perimeter frame and the ground. Lines from the line and pulley elevation mechanism preferably connect to the bed at points directly lateral to the center of gravity of the bed when loaded with a conventional motorcycle for balance during bed lowering and elevation.
2. Description of the Prior Art
There has long been a need to transport motorcycles by means other than driving them. As a result it has become a relatively common and hazardous practice to attempt to load motorcycles onto a conventional truck bed or equipment trailer. This is accomplished by pushing or riding the motorcycle up a ramp of some sort propped against the bed or trailer. Pushing a relatively large motorcycle up a ramp can be difficult or impossible for one person, and riding it up the ramp can be very dangerous. Should the motorcycle stall part way up the ramp, for example, there may not be adequate footholds to brace it against falling off the ramp and onto the rider.
Various trailers have been designed for carrying motorcycles and other vehicles. One such prior trailer is that of Zenna, U.S. Pat. No. 4,752,177, issued on Jun. 21, 1983 for a motorcycle trailer apparatus. Zenna includes a U-shaped outer frame with two parallel and spaced apart side portions and a forward cross-member interconnecting the side portions. Each side portion is fitted with a trailer wheel and tire and an upright hydraulic cylinder assembly. A motorcycle wheel receiving channel extends longitudinally midway between the frame side portions, and channel arms extend and join to a corresponding hydraulic cylinder assembly. The cylinder assemblies lower the wheel receiving channel within the outer frame to ground level to receive a motorcycle, and then raise the channel for trailer towing. A problem with Zenna is that the hydraulic cylinder assemblies make the trailer prohibitively expensive.
Behr, U.S. Pat. No. 5,536,131, issued on Jul. 16, 1996, teaches a utility trailer with level cargo support when lowered to and elevated from the ground. Behr includes a U-shaped outer frame and a generally planar bed within the outer frame, and a trailer hitch shaft extending forwardly from the outer frame. The outer frame and bed are interconnected on each side of the bed by forward and rearward pivot links. One end of each pivot link is rotatably fastened to a side of the bed and the other end is rotatably fastened to the outer frame through a torsion creating mechanism. A pulley and cable assembly is mounted to the forward end of the outer frame and the cable is connected to the forward end of the bed for raising and lowering the bed. A problem with Behr is that the bed loaded with cargo initially must be dragged over the ground before the bed rises. Another problem is that the bed and cargo must not only be lifted the distance required to clear the ground, but also moved substantially forward because of the upright orientation of the pivoting linkages, so that additional energy is required to generate bed and cargo momentum in a forward direction.
Shiels, U.S. Pat. No. 4,673,328, issued on Jun. 16, 1987, discloses a lift/tilt-bed trailer. Shiels includes a structure similar to that of Behr except that the pivot links are channel-shaped tracks and the bed has channel wheels which ride within the link tracks. A pulley is connected to a forwardly extending trailer hitch shaft and the cable extends generally horizontally back to the forward edge of the bed to raise the bed by rolling the bed wheels within the pivot link tracks. As a result of this construction, the bed can be raised and lowered in a level orientation, or the front only can be raised to tilt the bed into a ramp orientation. A problem with Shiels is that the bed, made heavy by loading with the cargo, must be initially dragged over the ground before it can rise. Another problem is that the bed and cargo must not only be lifted the distance required to clear the ground, but also moved substantially forward with the pivoting linkages, so that additional energy is required to generate forward bed and cargo momentum.
Fowler, U.S. Pat. No. 4,154,352, issued on May 15, 1979, reveals another motorcycle trailer. Fowler includes a trailer frame equipped to receive a motorcycle and having trailer supporting wheel assemblies. The wheel assemblies each including a fulcrum and linkage structure to pivot the wheels downwardly so that the trailer can roll on them and upwardly to lower the trailer frame to ground level for motorcycle loading and unloading. Wheel pivoting is accomplished by inserting a lever arm into a socket in each wheel assembly and applying lateral pressure to the arm. A problem with Fowler is that the user must lift not only the motorcycle but also the entire trailer frame during trailer loading and unloading.
Clark, U.S. Pat. No. 4,077,642, issued on Mar. 7, 1978, discloses a movable bed trailer. Clark includes a U-shaped frame mounted on a pair of oppositely disposed wheels and a bed mounted on double linkages within the frame. The bed is raised and lowered with a drive mechanism secured between the forward ends of the frame and bed. The bed remains in a substantially horizontal position during raising and lowering. A problem with Clark is that the bed loaded with cargo initially must be dragged over the ground before it can rise. Another problem is that the bed and cargo must not only be lifted the distance required to clear the ground, but also moved substantially forward with the pivoting linkages, so that additional energy is required to generate forward bed and cargo momentum.
Other related art includes Verschage, U.S. Pat. No. 4,372,572, issued on Feb. 8, 1983, for a tandem axle trailer with a hydraulic lift bed. The inclusion of a hydraulic system makes the trailer relatively expensive. The art also includes Harris, U.S. Pat. No. 5,288,197, issued on Feb. 22, 1994, for an equipment trailer; and Page, et al., U.S. Pat. No. 5,035,462, issued Jul. 30, 1991, for a utility vehicle chassis having a vertically adjustable bed. Harris and Page, et al., both teach truck beds within a truck body which are lowered between the rear wheels of the truck. A problem is that no provision is made for cargo vehicle transport with an already owned truck or car.
It is thus an object of the present invention to provide a trailer for transporting a cargo vehicle such as a motorcycle in tow behind a towing vehicle.
It is another object of the present invention to provide such a trailer having a bed within a perimeter frame which is lowered in a level orientation with a cable and pulley mechanism to ground level for loading and unloading the cargo vehicle and which is raised in a level orientation with the mechanism for towing.
It is still another object of the present invention to provide such a trailer in which the bed is raised without significant sliding of the bed over the ground.
It is finally an object of the present invention to provide such a trailer which requires no hydraulic bed elevation mechanisms and is otherwise highly economical to manufacture.